Process for rendering thermoplastic fibers paper translucent



United States 3,223,550 PROCESS FOR RENDERING THERMOPLASTIC FIBERS PAPER TRANSLUCENT Julian J. Hirshfeld, Decatur, Ala., assignor, by mesne assignments, to Monsanto Company, a corporation of Delaware No Drawing. Filed Jan. 16, 1962, Ser. No. 166,671 16 Claims. (Cl. 117138.8)

This invention is concerned with rendering paper composed of thermoplastic fibers translucent to light. More particularly this invention is concerned with rendering paper composed of acrylic fibers translucent to light.

An object of this invention is to produce translucent paper composed of synthetic fibers. Another object of this invention is to produce translucent paper composed of acrylic fibers. Other objects of this invention will be apparent from the following detailed description and claims.

Generally the objectives of this invention are accomplished by treating paper composed of thermoplastic fibers with an aqueous solution of tris(2,3-dibromopropyl)phosphate, phosphorous acid and phytic acid.

More specifically, the paper composed of synthetic fibers as described in a copending application, filed August 10, 1959, SN. 832,466, and now U.S. Patent No. 3,047,- 450, March 16, 1961, SN. 96,108, now abandoned, is padded with an aqueous or alcohol solution of the above identified agents varying from 5 percent to a 100 percent solution with the preferred being a 50 percent solution which includes any conventional solvent for the given compound such as aliphatic alcohols, benzene, toluene, etc. The sheets of paper are immersed in a solution, as described hereinbefore, of the agents for from 5 seconds to 15 minutes with the preferred being around 3 minutes more or less. The paper is then dried at any convenient temperature, such as 90 C. in a conventional drying oven, being sure not to heat to the discoloration point of the acrylic fibers Which is 165 C.

There are many uses to which this translucent paper may be applied. The paper may be used in windows to admit light but not images, such as in homes in Japan or in any place where light is required or desired, but no images; it may be used as tracing paper by anyone but especially engineers and architects; it may be used as a wrapper for anything which one may wish to tell what is inside the wrapping and many other uses as Well and it may be used for lamp shades.

The fibers which go to make up the paper of this invention are poly-acrylonitrile, copolymers, including binary and ternary polymers containing at least 80 percent by weight of acrylonitrile in the polymer molecule, or a blend comprising polyacrylonitrile or copolymers comprising acrylonitrile with from 2 to 50 percent of another polymeric material, the blend having an overall polymerized acrylonitrile content of at least 80 percent by weight. While the preferred polymers employed in the instant invention are those containing at least 80 percent of acrylonitrile, generally recognized as the fiber-forming acrylonitrile polymers, it will be understood that the invention is likewise applicable to polymers containing less than 80 percent acrylonitrile. The acrylonitrile polymers containg less than 80 percent acrylonitrile are useful in forming films, coating compositions, molding operation and lacquers.

For example, the polymer may be a copolymer of from 80 to 98 percent acrylonitrile and from 2 to 20 percent of another monomer containing the C C linkage and copolymerizable with acrylonitrile. Suitable monoolefinic monomers, include acrylic, alpha-chloroacrylic and methacrylic acids; methoxylmethyl methacrylate, beta-chloro- 3,223,550 Patented Dec. 14, 1965 ethyl meth-acrylate, and the corresponding esters of acrylic and alpha-chloroacrylic acids; vinyl chloride, vinyl fluoride, vinyl bromide, vinylidene chloride, l-chloro-lbromo-ethylene; methacrylonitrile; acrylamide and methacrylamide; alpha-chloroacrylamide; or monoalkyl substitution products thereof; methylvinyl ketone; vinyl carboXyl-ates, such as vinyl acetate, vinyl chloroacetate, vinyl propionate, and vinyl stearate; N-vinylimides, such as N-vinylphthalimide and N-vinylsuccinimide; methylene 'malonic esters; itaconic acid and itaconic esters; N- vinylcarbazole; vinyl furane; alkyl vinyl esters; vinyl sulfonic acid; ethylene alpha,beta-dicarboxylic acids or their anhydrides or derivatives, such as diethylcitraconate, diethylmesaconate, styrene, vinyl naphthalene; vinyl-substituted tertiary heterocyclic amines, such as the vinylpyridines and alkyl-substituted vinylpyridines, for example, 2-vinylpyridine, 4-vinylpyridine, Z-methyl-S-vinylpyridine, etc.; l-vinylimidazole and alkyl-substituted 1- vinylimidazoles, such as 2-, 4-, or S-methyl-l-vinylimidazole, and other C=C containing polymerizable materials.

The polymer may be a ternary or higher interpolymer, for example, products obtained by the interpolymerization of acrylonitrile and two or more of any of the monomers, other than acrylonitrile enumerated above. More specifically, and preferably the ternary polymer comprises acrylonitrile, methacrylonitrile, and 2-vinylpyridine. The ternary polymers preferably contain from to 98 percent of acrylonitrile, from 1 to 10 percent of a vinylpyridine or a l-vinylimidazole, and from 1 to 18 percent of another substance such as methacrylonitrile or vinyl chloride.

The polymer may also be a blend of a polyacrylonitrile or of a binary .interpolymer of from 80 to 99 percent acrylonitrile and from 1 to 20 percent of at least one other C C containing substance with from 2 to 50 percent of the weight of the blend of a copolymer of from 10 to 70 per-cent of acrylonitrile and from 30 to 90 percent of at least one other C:C containing polymerizable monomer. Preferably, when the polymeric material comprises a blend, it will be a blend of a copolymer of 90 to 98 percent acrylonitrile and from 2 to 10 percent of another mono-olefinic momomer, such as vinyl acetate with a sufiicient amount of a copolymer of from 10 to 70 percent of acrylonitrile and from 30 to 90 percent of a vinyl-substituted tertiary heterocyclic amine, such as vinylpyridine or -1-vinylimidazole, to give a dyeable blend having an overall vinyl-substituted tertiary heterocyclic amine content of from 2 to 10 percent based on the weight of the blend. Not only paper made from the above defined acrylics, but paper composed of blends of acrylics with artificial fibers such as cellulose acetate will be rendered translucent with the compounds of this invention.

The following examples are illustrated rather than limitative and all parts, proportions and percentages are by Weight unless otherwise indicated.

Example 1 A piece of paper composed of a blend of percent of a polymer of 94 percent acrylonitrile and 6 percent vinyl acetate and 15 percent of cellulose acetate, was immersed in a solution of 8 grams of tris-(2,3-dibromopropyl)phosphate and 12 grams of methyl alcohol. The paper was kept in the solution for 3 minutes and then removed and dried under a hood. After being dried, the paper was compared with an untreated piece of paper, and the treated paper possessed good translucent properties in comparison to the untreated paper.

Example 2 A piece of paper composed of a blend of 85 percent of a polymer of 94 percent acrylonitrile and 6 percent vinyl acetate and 15 percent of cellulose acetate, was immersed in a solution of 10 grams of tris-(2,3-dibromopropyl)phosphate and 10 grams of methyl alcohol. The piece of paper was kept in the solution for 3 minutes and then dried under a hood. After being dried, the paper was compared with an untreated piece and the treated paper possessed superior translucent properties.

Example 3 A piece of paper composed of a blend of 85 percent of a polymer of 94 percent acrylonitrile and 6 percent vinyl acetate and 15 percent of cellulose acetate, was immersed in a solution of 12 grams of tris-(2,3-dibromopropyl)phosphate and 8 grams of methyl alcohol. The paper was kept in the solution for 3 minutes and then removed and dried under a hood. After being dried the paper was compared with an untreated piece of paper, and the treated paper possessed excellent translucent properties in comparison to the untreated paper.

Example 4 A piece of paper composed of a blend of 85 percent of a polymer of 94 percent acrylonitrile and 6 percent vinyl acetate and 15 percent of cellulose acetate, was immersed in a solution of 20 grams of concentrated phosphoric acid, assay 85 percent to 87 percent. The paper was kept in the solution for 3 minutes and then removed and dried under a hood. After being dried, the paper was compared with an untreated piece of paper, and the treated paper possessed superior translucent properties in comparison to the untreated paper.

Example 5 A piece of paper composed of a blend of 85 percent of a polymer of 94 percent acrylonitrile and 6 percent vinyl acetate and 15 percent of cellulose acetate, was immersed in a solution of 15 grams of concentrated phosphoric acid, assay 85 percent to 87 percent, and 5 grams of water. The paper was kept in the solution for 3 minutes and then removed and dried under a hood. After being dried, the paper was compared with an untreated piece of paper, and the treated paper possessed good translucent properties in comparison to the untreated paper.

Example 6 A piece of paper composed of a blend of 85 percent of a polymer of 94 percent acrylonitrile and 6 percent vinyl acetate and 15 percent cellulose acetate, was immersed in a solution of 20 grams of concentrated phytic acid, assay 70 percent. The paper was kept in the solution for 3 minutes and then removed and dried under a hood. After being dried, the paper was compared with an untreated piece of paper, and the treated paper possessed superior translucent properties in comparison to the untreated paper.

Example 7 A piece of paper composed of a blend of 85 percent of a polymer of 94 percent acrylonitrile and 6 percent vinyl acetate and 15 percent cellulose acetate, was immersed in a solution of 15 grams of concentrated phytic acid, assay 70 percent, and 5 grams of water. The paper was kept in the solution for 3 minutes and then removed and dried under a hood. After being dried, the paper was compared with an untreated piece of paper, and the treated paper possessed superior translucent properties in comparison to the untreated paper.

Example 8 A piece of paper composed of fibers of a blend of 88 percent of one copolymer of 94 percent acrylonitrile and 6 percent vinyl acetate and 12 percent of another copolymer of 50 percent acrylonitrile and 50 percent methyl vinyl pyridine was immersed in a solution of 8 grams of tris(2,3-dibromopropyl)phosphate and 12 grams of methyl alcohol. The paper was kept in the solution for 3 minutes and then removed and dried in a hood. After being dried, the paper was compared with an untreated piece of paper and the treated paper possessed good translucent properties in comparison to the untreated paper.

Example 9 The exact process of Example 8 was repeated except the solution was composed of 10 grams of tris(2,3-dibromopropyl)phosphate and 10 grams of methyl alcohol. This treated paper possessed good translucent properties when compared to an untreated sample of paper.

Example 10 The exact process of Example 8 was repeated except the solution was composed of 12 grams of tris(2,3-dibromopropyl)phosphate and 8 grams of methyl alcohol. This treated paper possessed superior translucent properties when compared to an untreated sample of paper.

I claim:

1. An article composed of paper of acrylic fibers and a translucidizing agent selected from the group consisting of tris(2,3-dibromopropyl)phosphate, phosphoric acid and phytic acid.

2. An article composed of paper of acrylic fibers of a polymer of at least percent by weight of acrylonitrile and up to 20 percent by weight of another copolymerizable ethylenically unsaturated monomer impregnated with a translucidizing agent selected from the group consisting of tris(2,3-dibromopropyl)phosphate, phosphoric acid and phytic acid.

3. The article of claim 2 in which the paper is composed of fibers of a copolymer of 94 percent by weight of acrylonitrile and 6 percent vinyl acetate.

4. The article of claim 2 in which the paper is composed of fibers of a blend of copolymers comprising 88 percent by weight of one copolymer of 94 percent by Weight of acrylonitrile and 6 percent by weight of vinyl acetate, and 12 percent by weight of another copolymer of 50 percent by Weight of acrylonitrile and 50 percent by weight of methyl vinyl pyridine.

5. The article of claim 3 in which the translucidizing agent is tris(2,3-dibromopropyl)phosphate.

6. The article of claim 3 in which the translucidizing agent is phosphoric acid.

7. The article of claim 3 in which the translucidizing agent is phytic acid.

8. The article of claim 4 in which the translucidizing agent is tris(2,3-dibromopropyl)phosphate.

9. The article of claim 4 in which the translucidizing agent is phosphoric acid.

10. The article of claim 4 in which the translucidizing agent is phytic acid.

11. The article of claim 1 in which the paper is composed of a blend of acrylic fibers and cellulose acetate.

12. The article of claim 11 in which the paper is composed of percent by weight of fibers of copolymers of 94 percent by Weight of acrylonitrile and 6 percent by weight of vinyl acetate, and 15 percent by weight of fibers of cellulose acetate.

13. A method of rendering translucent paper composed of a blend of a fiber of 85 percent of 94 percent acrylonitrile and 6 percent vinyl acetate and 15 percent of cellulose acetate, comprising treating said paper with a 50 percent solution of tris(2,3-dibromopropyl)phosphate and methyl alcohol, removing said paper from said solution and drying same.

14. A method of rendering translucent paper composed of fibers of a blend of 88 percent of one copolymer of 94 percent acrylonitrile and 6 percent vinyl acetate and 12 percent of another copolymer of 50 percent acrylonitrile and 50 percent methyl vinyl pyridine, comprising treating said paper in a 50 percent solution of tris(2,3-dibrornopropyl)phosphate and methyl alcohol,

removing said treated paper from said solution and drying said paper.

15. A method of rendering translucent paper composed of acrylic fibers which comprises impregnating said paper with a solution of a translucidizing agent selected from the group consisting of tr-is(2,3-dibromopropyl)phosphate, phosphoric acid and phytic acid and drying said treated paper.

16. The method of claim 15 in which the concentration of said agent in said solution ranges from 5 to 100 percent.

References Cited by the Examiner UNITED STATES PATENTS Adams et a1. 117-130 Walter et a1. 117136 Bakalar et a1. 117-154 XR Ucci et a1. 162106 XR Birum 260461.3 12

WILLIAM D. MARTIN, Primary Examiner.

RICHARD D. NEVIUS, Examiner. 

15. A METHOD OF RENDERING TRANSLUCENT PAPER COMPOSED OF ACRYLIC FIBERS WHICH COMPRISES IMPREGNATING SAID PAPER WITH A SOLUTION OF A TRANSLUCIDIZING AGENT SELECTED FROM THE GROUP CONSISTING OF TRIS(2,3-DIBROMOPROPYL)PHOSPHATE, PHOSPHORIC ACID AND PHYTIC ACID AND DRYING SAID TREATED PAPER. 